This application is not referenced in any Microfiche Appendix.
This invention is concerned with a method of providing an internal circumferential shoulder in a cylindrical passageway and is exemplified by an installable load shoulder for a tubing or casing head, that is also frequently called a xe2x80x9cwellheadxe2x80x9d. xe2x80x9cTubingxe2x80x9d or xe2x80x9ccasingxe2x80x9d as used herein is inclusive of tubular products as used in drilling and completing oil and/or gas wells. The invention is particularly concerned with, but not limited to, an installable load shoulder positioned in a wellhead to support a tubing hanger or a casing hanger.
When a well is drilled into the earth it is customary to attach at the upper end of the well, such as at the upper end of surface casing, a wellhead which provides the super-structure for supporting smaller diameter tubular strings, whether strings of casing or strings of tubing. For this purpose a hanger is employed, either a casing hanger or a tubing hanger as the case may be that is secured to the upper end of a string of pipexe2x80x94that is, a string of casing or a string of tubing. Within the wellhead means must be provided for removably supporting the hanger and for this purpose it is customary to provide in the wellhead a circumferential load shoulder. A removable hanger, having casing or tubing suspended therefrom, is rested on the load shoulder. One problem with this arrangement is that the provision of an internally extending circumferential ledge within the interior of a wellhead reduces the internal diameter of the wellhead and thereby limits the diameter of drill bits or other tools or implements that may thereafter be inserted through the wellhead. The invention herein is an installable load shoulder that provides means for supporting a hanger, either a tubing hanger or a casing hanger within the wellhead and in a manner that the internal diameter of the wellhead is maximized. That is, a wellhead, having a full internal diameter opening therethrough can be equipped with a load shoulder that provides an inwardly protruding circumferential ledge on which a tubing or casing hanger can be supported and the installable load shoulder makes it possible to maintain a larger wellhead minimum internal diameter.
The concept of utilizing an installable load shoulder in a wellhead to support a tubing or a casing hanger is illustrated and described in U.S. Pat. No. 5,984,008 that issued on Nov. 16, 1999, entitled: xe2x80x9cINSTALLABLE LOAD SHOULDER FOR USE IN A WELLHEAD TO SUPPORT A TUBING HANGERxe2x80x9d. U.S. Pat. No. 5,984,008 is incorporated herein by reference and is a source of background information to the type of invention to which the present disclosure pertains. For further background information reference can be had to the following previously issued U.S. Patents:
This invention is a method of providing an internal circumferential shoulder in a cylindrical passageway and will be described and illustrated as the invention is employed to provide a wellhead installable load shoulder.
A wellhead is a metallic device affixed to the upper end of surface casing of an oil or gas well that is employed to suspend casing and/or tubing in the well. More specifically, a wellhead functions to provide the super-structure for suspending the upper end of a string of casing or tubing that extends from the earth""s surface down into a bore hole. In addition to providing the structures to support the weight of strings of tubing or casing, a wellhead functions to close off the upper end portion of casing or tubing and to provide communication as necessary with equipment whereby oil or gas produced by the well can be safely conveyed for refining and/or use without leakage to the environment.
Wellheads provide a vertical opening down which strings of tubing or casing or tools, such as drill bits can be inserted. The most typical construction of a wellhead employs the arrangement wherein the vertical cylindrical opening has two internal diametersxe2x80x94that is, a lower reduced internal diameter and an upper enlarged internal diameter, the differences in diameters providing an integral, circumferential ledge or shoulder that is used to support a tubing or casing hanger. The maximum diameter of any device passing through the typical wellhead is limited to the smaller diameter lower portion of the wellhead vertical opening that defines the load shoulder. One way of providing a larger diameter passageway is to make the load shoulder a separate element. In this way an internal circumferential groove is provided in the opening through the wellhead and a load shoulder can then be inserted into the groove to support a casing or tubing hanger when required. An example of an installable load shoulder for use in a wellhead is U.S. Pat. No. 5,984,008 entitled, xe2x80x9cINSTALLABLE LOAD SHOULDER FOR USE IN A WELLHEAD TO SUPPORT A TUBING HANGERxe2x80x9d. As previously stated, this patent is incorporated herein by reference. In this patent, a wellhead is provided with an internal circumferential groove and an integral toroidal member functions as an installable load shoulder. The integral toroidal member has a split therein that defines opposed first and second ends. The integral toroidal load shoulder can be collapsed so that the ends move toward each other providing an external diameter that is less than the internal diameter of the opening through the wellhead. When the circumferentially collapsed toroidal member is moved downwardly within the opening through the wellhead to the location of the enlarged internal diameter circumferential groove, the toroidal member can then resiliently expand to an increased external diameter within the circumferential groove. The end surfaces moving apart from each other so that the integral toroidal member is thereby seated within the circumferential groove. The toroidal member is configured so that when seated it extends circumferentially within the borehole opening and thereby provides a circumferential surface on which a tubing or casing hanger can be seated.
The present invention provides a load shoulder that accomplishes the same basic function as the installable load shoulder of U.S. Pat. No. 5,984,008 but has a completely different structural arrangement and is installed in the interior of a wellhead in a completely different way.
The present invention includes a toroidal member manufactured to have a predetermined radial cross-sectional configuration dimensioned to fit within an internal circumferential groove in a wellhead. After the toroidal member is manufactured with the predetermined cross-sectional shape, it is cut into at least three segments. In one embodiment, two spaced apart holes are first drilled and then tapped to provide internally threaded holes. The axes of the tapped holes are parallel to the toroidal member toroidal axis. After the holes are drilled and threaded, the integral toroidal member is cut into at least three segments. Cuts are made in the toroidal member through each of the tapped holes, the first two cuts being in planes that are parallel to each other to provide a first segment having end surfaces that are in planes parallel to each other. This first segment is a xe2x80x9ckeyxe2x80x9d segment, the importance of which will be described subsequently. The tapped holes are drilled at locations in the toroidal member that are spaced apart a distance less than the diameter of the toroidal member and at a distance apart from each other that is preferably about equal to the radius of the toroidal member. Therefore, after cuts are made in the toroidal member through the drilled and tapped holes, the toroidal member is then in two pieces, one piece being the portion of the toroidal member between the tapped holes which is a circumferential portion substantially less than one-half of the circumference of the toroidal member. The remainder is greater then a semi-circular portion of the toroidal member and it is cut into two, preferably about equal length portions, so that the toroidal member is now in three segments.
The segmented load shoulder can then be installed in a circumferential groove in a passageway by manually installing the two larger segments of the toroidal member (referred to as first and second segments) followed by insertion of the third or xe2x80x9ckeyxe2x80x9d segmentxe2x80x94that is, the segment between the spaced apart tapped holes. After the three segments are in position, a set screw is threaded into each of the tapped holes. This is one way of retaining the segments in position in the groove. In addition, to preserve the original internal and external diameter of the toroidal member, a spacer can be positioned between adjacent ends of the first and second segments, the spacer being preferably about the width of the saw blade employed to cut the segments. The spacer can be in the form of a spacer button. In this case, a short depth drilled opening is provided in one end surface of the first segment. A cylindrical portion of a spacer button is slidably inserted into the drilled opening. The spacer button has a head portion of a thickness equal to the thickness of the saw blade used to cut the toroidal member into segments.
The toroidal member as initially formed is configured to have an external circumferential surface that conforms to the shape of the groove provided in the cylindrical member, such as a wellhead and further, the toroidal member is preferably provided with a seating surface that is frusto-conical in configuration as typically employed on load shoulders.
A complete understanding of the invention will be obtained from the following detailed description of the preferred embodiments taken in conjunction with the attached drawings.